The 3 scenarios below are frequent patterns (itemsets) with constraints: (anti-monotone, monotone, succinct, convertible, etc.). State the characteristics of each constraint and briefly explain how to mine such patterns efficiently: Scenario a. The price difference between the most expensive item and the cheapest one in each pattern must be less than or equal to $90. Scenario b. The average price of all the items in each pattern is less than $20. Scenario c. The sum of the price of all the items (in each pattern) is between $100 and $200.